Cross flow heat exchanger with ducts in panel



United States Patent 3,194,308 CROSS FLOW HEAT EXCHANGER WITH DUCTS 1N PANEL John C. Haried, 1616 Kenilvvorth Place, Aurora, Ill. Filed May 28, 1962, Ser. No. 198,203 3 Claims. (Cl. 165-165) The present invention relates to improvements in heat exchange equipment and is more particularly concerned with the novel construction and assembly of a waste heat save-r and the novel arrangement of heat transfer units therein.

Although the herein disclosed novel arrangement of heat transfer elements is applicable to many various types of installations and in various types of heat exchange equipment, applic-ant has disclosed same installed in a novel structure particularly designed for pro-heating intake air for laundry drying equipment through the transfer of the heat removed from exhaust air from said drying equipment to the make-up air admitted to said equipment. It is therefore one of the advantages of the herein disclosed structure to remove heat from air discharge-d from a dryer and to utilize said heat to preheat incoming air and thereby reduce the costs of operation.

Heret-ofore, known types of heat exchange equipment have used coils of tubing, radiators and, more recently, helical coils of heat conductive sheet material having pr -formed fluid passageways therein such as for example, sheet-tubing of a kind sold commercially and known as Tube-in-Strip manufactured by Revere Copper and Brass, Incorporated, and hereinafter referred to -as tubular-sheet material. The advantages in using such tubular-sheet material are many. To name a few, particularly as applied to laundry drying equipment, such material minimizes the posibility of the air passageway becoming clogged by lint, dint, grease or other foreign particles of a kind that are entrained in the air stream and withdrawn from drying apparatus; has greater conductivity and affords a much more simplified structure and assembly and one that will withstand greater abuse than a coil of conventional form.

However, applicant has found that the use of such tubular-sheet material in the form of a helical coil is not efllcient particularly in a counter-flow heat exchange sysstem of the kind. herein disclosed. This is primarily because the heat to be transferred is not collected at the air intake end of such helical coils, but instead is distributed rat-her uniformly throughout the length thereof. As a result, there is an inefiicient transfer of heat, with the larger proportion thereof being retained in the original carrier stream and returned to its source.

It is proposed herein to arrange the tubular-sheet material in heat exchange equipment in a manner to impart maximum operating efficiency and it is, therefore, one of the objects of the invention to do so.

Another object of the invention is to provide novel equipment for removing heat from air exhausted there through and transferring it to make up air entering said equipment.

Another object is to provide novel equipment for preheating make up air entering drying apparatus hy the transfer of heat thereto from hot air exhausted from said apparatus.

Another object is to provide equipment of the character herein disclosed which is not expensive or difficult to manufacture, is highly efficient in use, inexpensive to operate, and which requires practically no servicing.

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The structure by means of which the above noted and other features and advantages of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawing, showing a preferred illustrative embodiment of the invention, in which:

FIG. 1 is a schematic view of representative heat exchange equipment of a character useful in dry cleaning establishments;

FIG. 2 is an enlarged elevational view of the heat transfer unit A, showing it partly broken away;

FIG. 3 is -a fragmentary sectional view taken substantially on line 3-3 of FIG. 2; and

FIG. 4 is a fragmentary perspective view of the tubulat-sheet material used in the heat transfer units A and B.

Referring to the exemplary disclosure in the accom panying drawings and particularly to FIG. 1, the heat exchange equipment illustrated is of a character primarily intended to effect transfer of heat extracted from exhaust air from the drying apparatus of a dry cleaning establishment into the make-up air delivered to said apparatus. It will become apparent from the disclosure herein that the heat exchange equipment per se and the heat exchange units therein are suitable for installation and use in any heat exchange system wherein different streams of air are flowed over heat exchange units in such manner as to reduce the temperature of one stream and increase the temperature of the other stream. In the present disclosure, the transfer of heat from the hot exhaust :air stream leaving a drying apparatus int-o the make-up air stream flowing thereto greatly reduces the operational costs of the laundry equipment because the pre-heated make-up air reduces the heating requirements of the heat source equipment of the dryer.

More particularly, the heat exchanger equipment comprises a housing 12 within which is arranged a pair of similar and novel construction heat transfer units A and B, which are interconnected one with the other and in series with a pump 13 operable to cause a heat transfer medium, such as water including an anti-freeze, to be circulated through and between the units.

The unit A is arranged in a housing compartment 14 so as to receive outside make-up air through opening 15. The air flows over and around the heat transfer components of unit A and is delivered, as by a duct 16, to the air intake side of drying apparatus (not shown) in a dry cleaning establishment. The hot exhaust air from the drying apparatus may be withdrawn through one or more ducts 17 and is delivered into a housing compartment 18, after passing through the heat transfer unit B, and is discharged to the atmosphere by a blower 19.

In the exemplary disclosure, heat from the hot exhaust air withdrawn from the drying apparatus is transferred to the fluid in unit B. The heated fluid in unit B is circulated through unit A, upon operation of pump 13, and the heat from said fluid is transferred to incoming or make-up air entering opening 15, so as to pre-heat same and thus minimize the amount of applied heat normally required in the drying apparatus to overcome the normal low temperature of incoming make-up air.

Maximum eificiency is obtained by use of units A and B when the heat transfer elements therein are fabricated from tubular-sheet material of the character referred to hereinabove. This material comprises a thin sheet of heat absorbent material, such as aluminum, copper, etc., having mutually spaced pre-formed passageways therein for the flow of a heat transfer medium therethrough. As

a i a 3,194,303 7 noted hereinabove, tubular-sheet material has been utilized heretofore as a heat transfer medium in air handling equipment but in suchmanner as to be extremelyinefiicient and wholly unsuited for the purpose intended. One

known use has been to coil a length of such tubular sheet 7 material helically' and wherein the heat transfer medium is flowed simultaneously into common ends of all of the passageways thereof. Because of this manner of flow, a

' as the" air entryxend of the unitA is'approachedr Z largepercentageof the heat transfer medium is notsub jected to nor is it effected by much of the air flowing Otherwise, stated, air flowing between the thereover. I helixes atthe outer periphery of the helical coil, where the heat transfer medium is entering-the coil, is subjected to a maximum amount ofh'eat transfer whereas asthe; axial center. is approached the temperature differential between the air flowand the heattransfer mediumis minimal. H a

In the present disclosure, applicant-has provided novel heat'exchange equipment that operates at maximum ciliciency to'remove heat from hotexhaust air flowing tfuere throughrand transfer said-heat to cooler make-up air entering the equipment. As best shown in FIGS. 2 and. 3, the unit A is comprisedof a casing 21 open at-its ends to provide a passageway for make-up air entering gcompartment 14. The heat transfer elements 22 (FIG. '4) comprise a plurality of sheets of tubular-sheet material of thecharacter described hereinabove each'fconsisting of a thin web 23 having mutually spaced fluid 'flow passageways '24 extending from edge to edge These.

elements 22 bridge the space betweenthe side walls of casing 21 and arespaced apart, in the FIGS. 2.3 disclosure, one ahovethe other in horizontal planes; with passageways ld'extending transversely of shell '21 so that air flowing from one end ,of said casing to the othenas and have maximum contact withwsaid elements 22 to in sure maximum vheat/transfer, between the air stream and the elements and fluid that is'flowed through passageways including an anti-freeze, is delivered to unit'A through p materialelements 22.1 As shown in FIG; 1, the tubular- 7 sheet material elements 22a in unit B are disposed in a vertical planes so as to permitpassage of air stream in a v vertical directioruas indicated bythe flow arrows 29.

Referring again to the detail disclosure in FIGS 2' and 3, the heat transfer fluid is delivered to unitA through conduit 27 at the :air' outlet-end of the unit; The fluid t flows through a first passageway 24b in the lowermost stripZZb andis conveyed by an external end connection v 31 to a first passageway 24c in a third strip22c, from where it is'conveyed to successive first passageways in j a the remaining strips 22d, 22e, 22f, which with the afore-- saidistrips ZZb and 22c are hereinafter termed alternate strips, through successive external end connections 31,itv being noted that :all'said first passageways are contained in a plane'which'is disposed substantially perpendicular to' the path of the a-ir stream'moving through the unit: In this manner'all of the incoming heat transfer medium is carried into the'path of theoutgoing air stream at the a region of theexit end of unit A, hence maximum heat transfer occurs in this region. I

Fluid flowing through the first passageway 24f in the uppermost strip 22 is delivered through an end connection 32 to passageway 24g of strip 22g, arranged intermediate thezaforesaid strips 22e and 22f. End connecfor makingiup"thecornplete unit. Successive series of passageways in said strips extending, in a direction toward the air inlet end of said unit A are connected in series As S'hOWIlyhflHt absorbent fluid, in this instance Water i In like manner maximum heat exchange influnit EB occurs at the'l'oiver or air entry end thereofgg'jf V It should be evident atthistime that applicant has 'pro vided a heat transfer unitithat operates' to ;prov-ide maximum temperature diiferences atthe make-up air inleti end thereof and fone. wherein there :isirninimum ltitEY-s ferenceto theiflow of air therethroughand with; few or v no, surfaces upon which dirtslint, and other foreignpanticles may collectiimexcessive amounts.

It isbelieved that'the inventiomits mode of construe tion'and assembly, and many of its advantages should be readily understood from theforegoingjwithout"furthen' descriptiomand-itfshould be :manifest'also thatwhile preferred-embodiment of the inventionj-has been shown-w and described for illustrative. purposes, thestructurahder; 1 tails are nevertheless capable ofwvide variation within the purview of the invention .as defined in wthe ppsnded claims.

the United States is What Ifclaimanddesire to isecurebytLettersPatent a 1. A-heat'transfer unit'comprising a casing definedsbyl spaced-apart'top andbottom wallsland spaced-apart'side walls and having oppositely disposed"airkinletand; air? discharge ends, }a -plurality ,ofsheetsgof heat transfermaterial-extending between a the[ casing side i walls and spaced from one anothergthroughout theirifullextent and 1 lying inplanes-which are substantially parallelfto {one A another, thereby to subdividetheiair.flowipaththroughl thecasing into a'plurality' oft'lesser parallel 'paths,means forming "a plurality of. fluid-flow passageways in each, sheet and jwhich'are disposednormal to the path of fair flowthrough the casing and shaveglength as"ltoextend. between the casingr side walls, means; fdisposedexternally of the: side walls'iandvconnecting those 'passagewaysof;

alternate sheets which are"containedfin planes substantially perpendicular to the 'air flow: path. in ."series with one another and thence inseries'with the correspondinglyl I disposed passageways gofan' intermediate :isheet land in such manner asto'formia' continuous fluid-flow passageway which extends progressively through all'of saidisheets and -in a 'directionjopposed to the directionofair 'flowl r throughisaid plurality of. air flow passage s, fa fluid inlet; connected ,to that sheet passageway at thejair discharge e'ndoffthe casing whichjconstitutesfthebeginningfofrthel continuous fluidiflowa'passageway, and a Qfluid outlet: con-i nected to' that" sheet passageway the; a rl inlet side of: the casing'which constitutestheqend 'ofi'the'jcontinuous 2. I A heat transferfunit as recited inclaim l inwhich' the means externally'of theside' wjalls comprises tubular; conduits. v f 1 Sf'Ahe'at transfereunit comprising a casing defined by spaced-apart top a'nd bottomiwalls and space cl -apart side" -t walls and having'oppositely disposed'fluidinlet and fluid 7 discharge ends, a pluralitysofsheet s ofr'heattransfer mate; Lrial extendinggbetween the-casihgside walls 'andls paced from oneanotherthroughout'their fullirte'htiand-lying V, in planesrfwhich are substantiallyaparallelt itooneian- 5 other, thereby'to subdividewthe fluid-flow path through the casing into a plurality of lesser parallel pathsymeans- 'forming a pluralityof fluid-flowfpassageways iniieachf said-sheet and which are disposed normal-tothe path of:

fluid flow through the casingiand'ha ve' lengthlas to extend between the casing side walls, endgconnectionsfdisposed externally of the side, wallstand connecting;thosepassage ways of alternate "sheetjsr-which arelscontairied infplanes substantially perpendicularto-the fluid flowjpath through a the casing in seriesrwith one another 'and'theuce: in series with'the correspondingly 'dis'p'osed 'passageways of. an in-: I termediate sheet and in suchfmainn'er as to forma con-i: V 'tinuous fluid-flow pas age ay which extends progressively 5 6 through all of said sheets and in a direction opposed to 2,375,702 5/45 Smith 165-145 the direction of fluid flow through said plurality of fiuid- 2,509,011 5/50 Moore 164-171 flow passages in the casing, a fluid inlet connected to that 2,691,279 10/54 Anderson 165-132 sheet passageway at the fluid discharge end of the casing 2,926,003 2/60 Pulsifer 164-170 which constitutes the beginning of the continuous fluid- 5 2,995,807 8/61 Gibbs 165-170 flow passageway, and a fluid outlet connected to that sheet 2,999,308 9/61 Pauls 165-164 passageway at the fluid inlet side of the casing which 3,077,031 2/ 63 Fromson 29-1573 cvozglstitutes the end of the continuous fluid-flow passage- FOREIGN PATENTS References Cited by the Examiner 10 f; g ft l d w1 zer an UNITED STATES PATENTS 310,329 12/55 Switzerland. 1,751,317 3/30 Gail 165-144 2,286,271 6/42 Higharn 29-1573 CHARLES SUKALO, Primary Examiner. 

1. A HEAT TRANSFER UNIT COMPRISING A CASING DEFINED BY SPACED-APART TOP AND BOTTOM WALLS AND SPACED-APART SIDE WALLS AND HAVING OPPOSITELY DISPOSED AIR INLET AND AIR DISCHARGE ENDS, A PLURALITY OF SHEETS OF HEAT TRANSFER MATERIAL EXTENDING BETWEEN THE CASING SIDE WALLS AND SPACED FROM ONE ANOTHER THROUGHOUT THEIR FULL EXTENT AND LYING IN PLANES WHICH ARE SUBSTANTIALLY PARALLEL TO ONE ANOTHER, THEREBY TO SUBDIVIDE THE AIR FLOW PATH THROUGH THE CASING INTO A PLURLAITY OF LESSER PARALLEL PATHS, MEANS FORMING A PLURALITY OF FLUID-FLOW PASSAGEWAYS IN EACH SHEET AND WHICH ARE DISPOSED NORMAL TO THE PATH OF AIR FLOW THROUGH THE CASING AND HAVE LENGTH AS TO EXTEND BETWEEN THE CASING SIDE WALLS, MEANS DISPOSED EXTERNALLY OF THE SIDE WALLS AND CONNECTING THOSE PASSAGEWAYS OF ALTERNATE SHEETS WHICH ARE CONTAINED IN PLANES SUBSTANTIALLY PERPENDICULAR TO THE AIR FLOW PATH IN SERIES WITH ONE ANOTHER AND THENCE IN SERIES WITH THE CORRESPONDINGLY DISPOSED PASSAGEWAYS OF AN INTERMEDIATE SHEET AND IN SUCH MANNER AS TO FORM A CONTINUOUS FLUID-FLOW PASSAGEWAY WHICH EXTENDS PROGRESSIVELY THROUGH ALL OF SAID SHEETS AND IN A DIRECTION OPPOSED TO THE DIRECTION OF AIR FLOW THROUGH SAID PLURLAITY OF AIR FLOW PASSAGES, A FLUID INLET CONNECTED TO THAT SHEET PASSAGEWAY AT THE AIR DISCHARGE END OF THE CASING WHICH CONSTITUTES THE BEGINNING OF THE CONTINUOUS FLUID-FLOW PASSAGEWAY, AND A FLUID OUTLET CONNECTED TO THAT SHEET PASSAGEWAY AT THE AIR INLET SIDE OF THE CASING WHICH CONSTITUTES THE END OF THE CONTINUOUS FLUID-FLOW PASSAGEWAY. 